Practice exercise (made-up values, not clinical guidance). A 64 kg patient has a fluid goal of 35 mL/kg/day and receives all fluid through a feeding tube. The formula is 84% free water and runs at 75 mL/h for 24 hours a day. The rest of the fluid is given as water flushes every 8 hours. What volume V is each flush? Round to the nearest whole number.
64 kg35 mL/kg/day84%75 mL/h · 24 hevery 8 h
V = mL
2.Enteral & parenteral nutrition calculationsHard
Practice exercise (made-up values, not clinical guidance). A child who weighs 7 kg receives 7.5% dextrose at 48 mL/h. Find the glucose infusion rate GIR in mg/kg/min. Round to two decimal places.
7 kg7.5%48 mL/h
GIR = mg/kg/min
3.IV fluids & fluid balanceMedium
Practice exercise (made-up values, not clinical guidance). The record shows a patient's intake and output for one 8-hour shift. The IV infusion ran at the rate shown for the whole shift. Find the total intake I in mL. Count ice chips as half their volume.
juice: 100 mLtea: 200 mLice chips: 240 mLIV infusion: 80 mL/h × 8 hIV antibiotic: 2 × 100 mL
I = mL
4.IV fluids & fluid balanceHard
Practice exercise (made-up values, not clinical guidance). A 1000 mL bag was started at 13:00 and runs by pump at 80 mL/h. How many mL V are left in the bag at 19:00?
1000 mL80 mL/h13:00 → 19:00
V = mL
3Solutions
1.Enteral & parenteral nutrition calculations
Answer: V = 243 mL
Needs and free water: energy needs are often estimated as kcal/kg/day × weight and protein needs as g/kg/day × weight. A formula is only partly water, so its free water = volume × water fraction; water flushes make up the rest of the daily fluid goal. Ideal body weight (Devine): IBW = 50 kg + 2.3 kg for every inch over 5 feet (60 in) for men, and 45.5 kg + 2.3 kg per inch over 60 in for women; 1 in = 2.54 cm. The formula is meant for adults at least 152.4 cm (5 ft) tall. The numbers are for practice only; at the bedside always follow local protocols and have high-risk doses double-checked.
Fluid goal
35·64 = 2240 mL/day
Free water from the formula
75·24 = 1800 mL
1800·0.84 = 1512 mL
Water still needed
2240 − 1512 = 728 mL/day
Volume per flush
24/8 = 3 flushes
V = 728/3 = 242.7 ≈ 243 mL
Answer
V = 243 mL
2.Enteral & parenteral nutrition calculations
Answer: GIR = 8.57 mg/kg/min
Parenteral nutrition: dextrose provides 3.4 kcal/g, amino acids 4 kcal/g and lipid emulsion the kcal/mL stated (2 kcal/mL for 20%, 1.1 kcal/mL for 10%). Grams = % × mL/100. Non-protein kcal (NPC) = dextrose + lipid kcal; nitrogen = protein/6.25. The glucose infusion rate (GIR) in mg/kg/min = dextrose mg/(kg × minutes). The numbers are for practice only; at the bedside always follow local protocols and have high-risk doses double-checked.
Dextrose concentration
7.5% = 75 mg/mL
Dextrose per minute
75·48/60 = 60 mg/min
Per kilogram
GIR = 60/7 = 8.571 ≈ 8.57 mg/kg/min
Answer
GIR = 8.57 mg/kg/min
Shortcut: GIR = % dextrose × mL/h/(6 × kg).
3.IV fluids & fluid balance
Answer: I = 1260 mL
Intake and output: intake counts everything that goes in (oral fluids, IV infusions, IV medications and flushes, tube feeds); ice chips count as half their volume. Output counts urine, drains, vomit and other losses. Balance = total intake − total output; a negative balance is a net loss. The numbers are for practice only; at the bedside always follow local protocols and have high-risk doses double-checked.
Add the intake
oral: 100 + 200 = 300 mL
ice chips: 240/2 = 120 mL
IV infusion: 80·8 = 640 mL
IV antibiotic: 2·100 = 200 mL
I = 1260 mL
Answer
I = 1260 mL
4.IV fluids & fluid balance
Answer: V = 520 mL
Infusion time: time (h) = volume to infuse (mL)/rate (mL/h); use the volume still left in the bag, not the bag size. Volume infused = rate × time. Convert decimal hours to hours and minutes with the fraction × 60 (0.5 h = 30 min, not 50 min). The numbers are for practice only; at the bedside always follow local protocols and have high-risk doses double-checked.